Cruz, seen here announcing his presidential candidacy in March, has the highest minimum net worth of the five senators running for president. But even he doesn't crack the list of the top 100 wealthiest members of Congress. (Tom Williams/CQ Roll Call File Photo)

When it comes to personal wealth, the five senators running for president aren’t exactly rolling in cash — by congressional standards, that is. Ted Cruz , the richest senator running for president, doesn’t even crack the top 100 on the Roll Call Wealth of Congress Index, an annual ranking of members by minimum net worth. The Texas Republican comes in at No. 141, with a minimum net worth of at least $1.8 million. The median American net worth was nearly $69,000 in 2011, the year for which the most recent data is available from the Census Bureau.

The 10 Richest Members of Congress in 2015

Relative to Donald Trump, the GOP front-runner in most national polls, the senators running for president are downright poor. Forbes estimates Trump’s net worth at $4 billion. A mong the four senators vying for the GOP nomination, the poorest is Florida Sen. Marco Rubio , who registers a negative net worth.

The source of candidates' personal fortunes can sometimes be more meaningful — in terms of the image they project and the donor connections they foster — than the sheer value of their assets.

So where does the candidates' wealth come from?

Cruz and his wife, Heidi Nelson Cruz, separately or jointly hold hundreds of thousands of dollars in corporate securities stock, much of which is vested in various Goldman Sachs funds.

Nelson Cruz worked for the investment firm before taking an unpaid leave for the duration of her husband’s campaign. Her non-investment income from Goldman is listed as “greater than $1,000,” but it’s undoubtedly worth far more. As is the case with all members, the actual value of the Cruz family’s total assets is likely higher than the senator's minimum net worth suggests, given that members are only required to report the value of their assets in ranges. Roll Call only calculates the minimum value, removing the possibility of overestimating wealth.

Cruz counts several valuable pension plans from his law firm among his assets, as well as a $500,000 loan to his Senate campaign.

The conservative firebrand is not without liabilities. He has a mortgage worth $250,001 to $500,000 on a property acquired in 2011, as well as a $50,001 to $100,000 loan from Goldman Sachs and two lines of credit worth a total of at least $25,000.

The gap between Cruz and the second richest senator running for president, Kentucky's Rand Paul , is wide. With a minimum net worth of $385,000, the former ophthalmologist is ranked 288 on the Roll Call Wealth of Congress Index.

True to his libertarian leanings, Paul owns at least $15,000 in silver coins. He has another $15,000 invested in a USAA precious metals and minerals fund. The bulk of his assets include similarly valued mutual funds and several college savings accounts for his children.

Two of his Vanguard mutual funds — one held jointly with his wife — are worth at least $100,000 each. Paul also owns numerous rental properties in Texas, Kentucky and Florida, most of minimal value except for a property worth a minimum of $100,000 in the Sunshine State. Paul closed one $100,000 mortgage and took on another jointly with his wife after refinancing his home in July 2014.

The only current member jockeying for the Democratic nomination, Vermont Sen. Bernard Sanders , has a minimum net worth of $163,000. The two-term senator and former congressman is No. 340 on the Wealth of Congress Index and is third among all senators pursuing the White House.

Sanders' personal finances befit his populist economic message. The only wealth he lists in his own name is an approximately $5,000 pension from the city Burlington, where he was mayor during the 1980s. All of his assets — mostly mutual funds — are held by his wife, the former president of Burlington College.

Sanders carries at least $10,000 in liabilities on a Visa card credited by the Congressional Federal Credit Union in 1991. He has another $15,000 on a Visa card the Senate Federal Credit Union credited in 2006, the year he was elected to the Senate. (All members are required to list credit card purchases exceeding $10,000, even if it's not credit card debt.)

The senator who suffered the worst year in the rankings? South Carolina's Lindsey Graham slipped more than 100 spots in Roll Call’s Wealth of Congress Index, from 255 to 366. His minimum net worth fell from $537,000 to just $86,000 in 2014. Graham got out from under some of his debt, reducing the mortgage on his primary residence — but his assets took a nose dive during 2014, mainly because he no longer rents out a Washington, D.C., property that was valued at a minimum of $500,000 on his previous financial disclosure report. (He still owns the property, but is not required to list it as an asset because it is not bringing in any revenue from rent.) Graham's Sunshine State colleague knows a thing or two about declining personal fortunes.

Rubio isn't just the poorest member running for president; he's also the only one of the five whose net worth is solidly in the red, sinking even deeper last year than the year before. With a minimum net worth of negative $163,000, he now ranks 468.

The $450,000 weight around Rubio's neck is made up of two mortgages and one home equity line of credit, all incurred before he was elected to the Senate.

Writing a book is almost a prerequisite for launching a presidential bid these days. And although royalties and advances don't count as assets, and therefore don't factor into net worth, three of the five senators running for president have received payment for their prose, likely cushioning their personal finances in 2014.

Cruz collected a $190,000 advance for "A Time for Truth: Reigniting the Promise of America," published this summer. Meanwhile, Rubio's 2012 memoir delivered diminishing returns in 2014, earning him at least $315,000 less in royalties than the year before.